After appearing in Trekkies, Koerner achieved a minor celebrity status. He appeared as "The Star Trek Geek" in fifteen episodes of the short-lived Comedy Central game show Beat the Geeks. He also guest-starred as the character "Frank" in two episodes of The Drew Carey Show. The first of these was the annual April Fool's Day episode for 2001, which included many Star Trek and sci-fi references and jokes. Among the jokes were a Trek-style doorway in the office, Lewis mentioning a girl at a sci-fi convention that weighed under 200 pounds, and Frank referring to his house as "the Babylon 2 station." Koerner returned for his second appearance, later that year, when Lewis and Oswald (Diedrich Bader) built a killer robot to compete in a Battlebots-style competition. Frank's robot was victorious after Lewis and Oswald's self-destructs.

Koerner's story was followed up in 2005's Trekkies 2. He was also lead visual effects artist for that film, creating the entire opening animation sequence. He was credited as a research consultant on this film, as well. He has also appeared in the fan filmStar Trek: Hidden Frontier, playing the role of Captain Jillson. In 2013 he joined the creative staff of the fan series Star Trek Continues as a digital visual effects artist. Notable contributions he made for that series were his CGI co-builds with Doug Drexler of an Orion and a Tellerite ship, which were based on Star Trek: The Original Series era designs of Matt Jefferies, for the second episode "Lolani".

After his spell at Eden FX, Koerner's career as a digital artist took off when he worked as such on films like The Day After Tomorrow (2004), Serenity (2005), Superman Returns (2006, directed by Bryan Singer), and Speed Racer (2008, featuring music by Michael Giacchino). He was also a digital artist on the hit television series Alias and Lost, both created by J.J. Abrams. Koerner's work as a digital modeler on the Ronald D. Moore-produced series Battlestar Galactica earned him and his fellow visual effects team members an Emmy Award nomination in 2005.

Koerner often spells his name with an umlaut over the 'o', so that his name is written Gabriel Köerner.